The present invention relates to the field of angioplasty, and, in particular, to a method and apparatus for supporting a guide wire during a catheter exchange.
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating types of vascular diseases. In particular, angioplasty is widely used for opening stenoses in the coronary arteries, although it is also used for treatment of stenoses in other parts of the vascular system.
The most widely used form of angioplasty makes use of a dilatation catheter which has an inflatable balloon at its distal end. A guide catheter is positioned in the patient to establish a path to the heart. Then, the dilatation catheter is introduced into the guide catheter, and using fluoroscopy, the physician guides the dilatation catheter through the coronary arterial system until the balloon is positioned across the stenosis. The balloon is then inflated by supplying fluid pressure through an inflation lumen in the catheter to the balloon. The inflation of the balloon causes stretching of the artery and pressing of the lesion into the artery wall to re-establish acceptable blood flow through the artery, once the balloon is deflated and removed.
Two types of balloon dilatation catheters which are presently in common use are "full length over-the-wire" catheters, and "single operator exchange" style catheters. In a full length over-the-wire catheter, a guide wire lumen is provided in the catheter extending substantially the full length of the catheter. The guide wire lumen is separate from and alongside or coaxial with an inflation lumen in the catheter so that a guide wire can be used to establish the often tortuous path to and through the stenosis. The dilatation catheter is then advanced over the guide wire until the balloon is positioned across the stenosis for inflation and treatment. If a full length over-the-wire catheter in place over the guide wire is to be exchanged for a second full length over-the-wire catheter, an extension must be placed on the guide wire (or a longer guide wire must be used initially) so that a portion of the guide wire may always be held as the catheters are exchanged.
In a "single operator exchange" style angioplasty catheter, the catheter has an inflation lumen extending therethrough, but a guide wire extends through a guide wire lumen in the catheter that is only in a distal portion of the catheter. Thus, the guide wire lumen is shorter than the inflation lumen and shorter than the overall length of the catheter. The single operator exchange style catheter structure provides an alternative method for exchanging dilatation catheters, since the proximally exposed guide wire can be held while catheters are exchanged. The length of the catheter that must slide over the guide wire is lessened (the guide wire lumen is reduced to less than the length of exposed guide wire outside of the proximal end of the guide catheter.
In a single operator exchange style catheter, when one desires to exchange catheters, the guide wire is grasped proximally of a Y-adaptor of the guide catheter to maintain the guide wire in position across the stenosis. The catheter shaft is then grasped proximally of the Y-adaptor and backed off of the guide wire. After withdrawing most of the catheter out of the guide catheter, the proximal end of the guide wire lumen is positioned adjacent the proximal end of the Y-adaptor. At this point, to maintain the position of the guide wire across the stenosis while backing the balloon catheter off the guide wire, the guide wire must be grasped at some point spaced proximally of the proximal end of the guide wire lumen and the catheter withdrawn until the proximal end of the guide wire lumen is at this point of grasping. Then, the user must once again grasp the guide wire at some point spaced proximally to the proximal end of the guide wire lumen and pull the catheter proximally until the proximal end of the guide wire lumen is at this point of grasping.
This sequence must be repeated until the distal end of the guide wire lumen is proximal of the proximal end of the Y-adaptor. At this point, the guide wire is grasped or secured from longitudinal movement distally of the distal end of the guide wire lumen to maintain the position of the of the guide wire across the stenosis. With the guide wire so fixed, the dilatation balloon catheter is then withdrawn proximally from the remaining portion of the guide wire so that a second dilatation balloon catheter may be fed onto the proximal end of the guide wire and then advanced distally over the guide wire to the stenosis.
This process of repeatedly grasping the guide wire at points proximal to the proximal end of the guide wire lumen zone is tedious and time-consuming. The primary obstacle dictating the iterative grasping of the guide wire is that the guide wire will bow or buckle if the guide wire is grasped too far proximally of the proximal end of the guide wire lumen. Buckling may cause kinking of the guide wire, or may cause the distal end of the guide wire to move within the stenosis or become dislodged from the stenotic area. To avoid the buckling of the wire and to maintain the guide wire position across the stenosis, the guide wire must be grasped at relatively short distances (e.g., one inch increments) proximal to the proximal end of the guide wire lumen, resulting in the numerous repetitive iterations of proximal grasping of the guide wire. Thus, although the single operator exchange style catheters provide an alternative catheter exchange arrangement, they do not necessarily overcome the difficulty of maintaining guide wire position across the stenosis while removing the catheter from the guide wire, as well as avoiding or minimizing the danger of kinking, bowing or buckling the guide wire.